Construction on the Interstate 680 express lanes project will lead to a pair of overnight freeway ramp closures during the next week, according to the Metropolitan Transportation Commission (MTC).
The southbound I-680 off-ramp at Alcosta Boulevard in San Ramon is scheduled to be closed this Monday through Thursday from 8 p.m. to 5 a.m. each night.
Then in Alamo, the Stone Valley Road on-ramp to northbound I-680 is set to be closed on Friday and Saturday from 9 p.m. to 5 a.m.
The work necessitating the temporary closures includes directional boring and installation of conduit under the ramps to connect to power sources, according to MTC officials.
For the Alcosta ramp, the detour will instruct drivers to continue on I-680 southbound to the Dublin Boulevard exit, where they will be directed to northbound I-680, which they can drive on until the Alcosta Boulevard exit in that direction.
For the Stone Valley closure, the detour will direct drivers to get on I-680 south at Stone Valley Road, then get off at El Pintado Road and find the northbound I-680 on-ramp at that interchange.
Crews will also continue their regular overnight work near I-680 medians in both directions through the San Ramon Valley as they proceed with the $49 million express lanes project, slated to be completed this fall. Intermittent and alternating lane closures near the medians will occur, MTC officials said.
As proposed, the congestion-relief project would replace existing high-occupancy vehicle (HOV) lanes with express lanes on southbound I-680 from Rudgear Road to Alcosta Boulevard and on northbound I-680 from Alcosta to Livorna Road in Alamo -- approximately 23 miles overall.
The express lanes would be free to access for carpools, vanpools, public transit, motorcycles and eligible clean-air vehicles while other solo drivers could pay a toll to use the lanes. Toll lane hours and rates have not been finalized, according to the MTC.